The present invention relates to crosslinked polysaccharides and methods of preparation thereof and, in particular, glyoxal and glyoxal/titanium crosslinked guar and methods of preparation thereof.
Guars are commercially available in several forms, including derivatized and underivatized. Among the derivatized forms are cationic, non-ionic, and anionic, and combinations of cationic, non-ionic, and anionic. Among the derivatized guar splits and gums are carboxyl methyl guar gums, hydroxypropyl guar gums, and hydroxypropyl trimethylammonium guar gums, which are commercially available materials used in a variety of applications and are typically made by a “water-splits” process, wherein material, known as guar “splits”, derived from guar seeds undergoes reaction with a derivatizing agent in an aqueous medium.
These various types of guars have been used extensively in many fields. Among the fields of use where properties of guars are useful are personal care, household care, and pet care formulations, including but not limited to: shampoos, body washes, hand soaps, lotions, creams, conditioners, shaving products, facial washes, neutralizing shampoos, personal wipes, other hair care products and skin treatments.
Guars are conventionally produced by milling at an alkaline pH and then crosslinked with Borax (sodium tetra borate). Borax is commonly used as a processing aid in the reaction step of the water-splits process to partially crosslink the surface of the guar splits and thereby reduces the amount of water absorbed by the guar splits during washing. The borate crosslinking takes place under alkaline conditions and is reversible, allowing the product to hydrate under acidic conditions.
However, due to regulatory concerns regarding the boron content of materials used in personal care applications, it has now become desirable to make derivatized guar without using any boron-containing crosslinker.
Another problem with conventional cationic guars is the production of trimethylamine (“TMA”) impurity when milling at high temperatures. Trimethylamine is an undesirable impurity in personal care formulations due to its fishy smell.
A still further problem with conventional guars is undesirable yellowing whereas certain end use formulations require white guar.
What is needed is an alternative to boron crosslinking as a process aid to simplify the manufacture and handling of polysaccharide thickeners, including derivatized polysaccharide thickeners, such as derivatized guars.
It is also desirable to produce improved guars which are crosslinked, boron-free, and comprise substantially no trimethylamine or no trimethylamine at all.
It is further desired to provide cationic guars which improve silicone deposition in personal care formulations.